Dental X-ray diagnostic installation

Abstract

An exemplary embodiment comprises an exposure unit including an X-ray tube and a cassette holder rotatable about vertical axes and between which the head of the patient is disposed. A radiation detector is disposed at the cassette holder for supplying an electrical signal corresponding to the dose rate when it is struck by X-rays and being interconnected with an X-ray tube voltage controller and a dose rate regulator in such manner that the X-ray tube voltage is influenced by the output of the radiation detector to control the dose rate to a value producing an optimum film blackening. A function generator determining the speed of the exposure unit is provided in which a speed curve is stored given which the radiation dose influencing the film is approximately constant.

I claim as my invention: 
     
       1. A dental X-ray diagnostic installation comprising an exposure unit including an X-ray tube and a cassette holder, movable about a head location lying between the X-ray tube and the cassette holder for producing general exposures, a radiation detector which supplies an electrical output signal corresponding to the dose rate when it is struck by X-radiation being attached to the cassette holder, automatic exposure control means coupled with said radiation detector and including a dose rate regulator and an X-ray tube voltage control means interconnected in such manner that the X-ray tube voltage is influenced by the output signal of the radiation detector for the purpose of the control of the dose rate to a value producing an optimum film blackening, a single motor coupled with said X-ray tube and with said cassette holder for effecting movement thereof about the head location for the production of a general exposure during an exposure operation, and a function generator coupled with said single motor, said function generator storing respectively optimum velocity curves for various patient constitutions and controlling the speed of the single motor during an exposure operation for a given patient constitution such that the radiation dose influencing successive locations of an X-ray film in the cassette holder is approximately constant for the given patient constitution, and such that the dose rate regulator is only required to vary the radiation output from the X-ray tube within a relatively small range in comparison to the range which would be required in the absence of control of the speed of said single motor by said function generator.